Conductive film based on cation-pi crosslinking polyimide and preparation method thereof

Abstract

The invention belongs to the technical field of polyimide composite materials, and relates to a cation-pi crosslinking-based polyimide conductive film and a preparation method thereof. The preparation method comprises the following steps: preparing polyamide acid powder; the preparation method comprises the following steps: dissolving 3-5 parts of polyamide acid powder in a solvent, adding 0.01-0.03 part of a modifier and 0.08-0.12 part of a conductive polymer monomer after the polyamide acid powder is completely dissolved, and reacting at 0-5 DEG C to obtain an intermediate product; adding 1-3 parts of a transition metal organic complex and 0.03-0.06 part of an oxidizing agent into the intermediate product, reacting, adding 0.1-0.15 part of a dehydrating agent into the intermediate product, and carrying out a dehydration reaction to obtain a mixed solution; and carrying out thermal forming on the mixed solution at 100-200 DEG C to obtain the cation-pi cross-linked polyimide conductive film. The problem that an existing cation-pi cross-linked polyimide material is not conductive is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyimide composite materials, and particularly relates to a cation-π cross-linked polyimide conductive film and a preparation method thereof. Background Art

[0002] Polyimide (abbreviated as PI) is widely used in the fields of electronics, aerospace, flexible displays, etc. due to its excellent mechanical properties, thermal stability and chemical stability. However, traditional polyimide films have deficiencies in conductivity, which limits their application in some high-end electronic devices. In recent years, with the increasing demand for high-performance materials, the development of polyimide films with good conductivity has become a research hotspot.

[0003] The cation-π interaction is a non-covalent interaction with strong binding force and dynamic reversibility, which can effectively enhance the mechanical properties and thermal stability of materials. By introducing cations and electron-rich groups into the polyimide molecular chain, a cation-π cross-linked structure can be constructed, thereby significantly improving the performance of polyimide films.

[0004] Although there have been studies on enhancing the mechanical properties and thermal stability of polyimide through cation-π interactions, most of the studies focus on non-conductive fields. For example, Chinese Patent Publication No. CN116925420A discloses a polyimide aerogel based on cation-π cross-linking and its preparation method, as well as a composite aerogel based on it and its preparation method.

[0005] Currently, there is almost no research on cation-π cross-linked polyimide conductive films. There are still challenges in the balance between conductivity, mechanical properties and thermal stability of existing conductive films, and it is difficult to simultaneously meet the comprehensive requirements of high-performance electronic devices for materials. Summary of the Invention

[0006] The purpose of the present invention is to provide a cation-π cross-linked polyimide conductive film and a preparation method thereof, which solve the problem of non-conductivity existing in existing cation-π cross-linked polyimide materials.

[0007] The present invention is realized through the following technical solutions: A preparation method of a cation-π cross-linked polyimide conductive film includes the following steps: 1) Prepare polyamic acid powder; 2) Dissolve 3-5 parts of polyamic acid powder in a solvent. After complete dissolution, add 0.01-0.03 parts of a modifier and 0.08-0.12 parts of a conductive polymer monomer, and react at 0-5°C to obtain an intermediate product; 3) Add 1 - 3 parts of transition metal organic complex and 0.03 - 0.06 parts of oxidant to the intermediate product. After the reaction, add 0.1 - 0.15 parts of dehydrating agent thereto and conduct a dehydration reaction to obtain a mixed solution; 4) Thermoform the mixed solution at 100 - 200 °C to obtain a cation-π crosslinked polyimide conductive film.

[0008] Furthermore, the preparation process of the polyamic acid powder is as follows: Ultrasonically disperse 4 - 6 parts of diamine monomer and 5 - 8 parts of dianhydride monomer in N,N-dimethylacetamide, react under the protection of inert gas until completely dissolved, and obtain a polyamic acid solution after reaction at room temperature; Recrystallize the polyamic acid solution in methanol for further purification, filter and then freeze-dry to obtain the polyamic acid powder.

[0009] Furthermore, the dianhydride monomer is one or more of pyromellitic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0010] Furthermore, the diamine monomer is one or more of 4,4'-diaminodiphenyl ether, 2-(4-aminophenyl)-1H-benzimidazol-2-amine, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, p-phenylenediamine, 2,2-bis(4-aminophenoxy)hexafluoropropane.

[0011] Furthermore, the modifier is one or more of divinylbenzene, glycidyl acrylate, 3-aminopropyltriethoxysilane or aminopropyltrimethoxysilane.

[0012] Furthermore, the conductive polymer monomer is one or more of 3-vinylaniline, N-vinylcarbazole, 4-vinyl-1,3-dihydro-2H-indol-2-one.

[0013] Furthermore, the transition metal organic complex is one or more of acetylferrocene, zinc tetraphenylporphyrin, cyclopentadienyliron dicarbonyl dimer, lithium iron phosphate, diiron nonacarbonyl.

[0014] Furthermore, the oxidant is one or more of hydrogen peroxide, potassium persulfate, iron perchlorate, benzoyl peroxide.

[0015] Furthermore, the dehydrating agent is one or more of pyridine, isoquinoline, acetic anhydride, imidazole or triethylamine.

[0016] The present invention also discloses a cation-π crosslinked polyimide conductive film prepared by the above preparation method, with a tensile strength reaching 1300 - 2500 MPa and a thermal conductivity reaching 1.5 - 3.0 S·cm -1 .

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses a preparation method of a cation-π crosslinked polyimide conductive film, which etherifies the amino group of polyamic acid with a vinyl modifier, then introduces a conductive polymer monomer, and conducts oxidative polymerization under low-temperature oxidation conditions to form a stable conductive polymer in the polyimide structure, and further cures to form a polyimide conductive film. In this strategy, the aromatic dianhydride structure of polyamic acid interacts with transition metal cations to form a dynamic reversible redox system, which can activate the oxidative polymerization process and accelerate the reaction. By introducing polyamic acid and a conductive polymer monomer containing an aromatic ring, a cation-π crosslinked polymer network is constructed, and by adjusting the types of cations and aromatic rings, the strength and selectivity of crosslinking are precisely controlled, thereby enhancing the mechanical properties, thermal stability and chemical stability of the polymer. In addition, the prepared conductive film not only has excellent heat insulation performance, but also endows the material with electrical properties by modifying the conductive polymer on the main chain.

[0018] Furthermore, the diamine monomer (containing amino - NH2) and the dianhydride monomer (containing acid anhydride group -CO-O-CO-) react in a polar aprotic solvent N,N-dimethylacetamide (DMAC). At room temperature, this reaction is a ring-opening addition reaction. The specific process is that the acid anhydride group of the dianhydride monomer opens and reacts with the amino group of the diamine monomer to form an amide bond (-CONH-), thereby generating polyamic acid. After the reaction ends to form a polyamic acid solution, there are diamine and dianhydride monomers in the solution. By purifying in methanol, the macromolecular polymer polyamic acid further precipitates, and the small molecule substances dissolve in methanol, thus separating the monomers from the product. Description of the Drawings

[0019] Figure 1 For the comparison of the tensile test results of the polyimide conductive films of Examples 1 - 8 and the comparative examples; Figure 2 For the comparison of the conductivity and ion leaching test results of the polyimide conductive films of Examples 1 - 8 and the comparative examples; Figure 3 For the comparison of the ion leaching test results of the polyimide conductive films of Examples 1 - 8 and the comparative examples. Detailed Embodiments

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the following further detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments.

[0021] The components described and illustrated in the accompanying drawings and embodiments of the present invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the present invention claimed, but merely represents a selected embodiment of the present invention. Based on the accompanying drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

[0022] It should be noted that the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, element, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to the process, element, method, article or device.

[0023] The present invention discloses a preparation method of a cation-π crosslinked polyimide conductive film, comprising the following steps: 1) Ultrasonically disperse 4-6 parts of diamine monomers and 5-8 parts of dianhydride monomers in N,N-dimethylacetamide, react under the protection of inert gas until completely dissolved, react at room temperature to obtain a polyamic acid solution, recrystallize in methanol for further purification, filter and then freeze-dry to obtain polyamic acid powder.

[0024] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide, add 0.01-0.03 parts of modifier and 0.08-0.12 parts of conductive polymer monomer after complete dissolution, and react at 0-5 °C for standby.

[0025] 3) Add 1-3 parts of transition metal organic complex and 0.03-0.06 parts of oxidant to step 2), react at low temperature for 3 h to obtain a mixed solution; 4) Add 0.1-0.15 parts of dehydrating agent to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform at 200 °C to obtain a cation-π crosslinked polyimide conductive film.

[0026] The following further detailed description is made on the present invention in conjunction with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0027] Example 1 1) Ultrasonically disperse 4 parts of 4,4'-diaminodiphenyl ether, 2-(4-aminophenyl)-1H-benzimidazol-2-amine with a mass ratio of 3:1, and 5 parts of pyromellitic dianhydride in 50 mL of N,N-dimethylacetamide. React for 0.5 h under the protection of inert gas until completely dissolved, and then react at room temperature for 5 h to obtain a polyamic acid solution. Further purify it by recrystallization in methanol, filter, and then freeze-dry for 24 h to obtain polyamic acid powder.

[0028] The reaction formula is as follows:

[0029] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.01 part of divinylbenzene and 0.08 part of 3-vinyl aniline, and react at 0 °C for later use.

[0030] The reaction formula is as follows:

[0031] 3) Add 1 part of acetylferrocene and 0.03 part of hydrogen peroxide-potassium persulfate with a mass ratio of 1:9 to the mixture in step 2), and react at 0 °C for 3 h to obtain a mixed solution; 4) Add 0.1 part of pyridine to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform at 200 °C to obtain a cation-π crosslinked polyimide conductive film.

[0032] The reaction formula is as follows:

[0033] Example 2 1) Ultrasonically disperse 5 parts of 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl sulfone with a mass ratio of 3:2 and 6 parts of 3,3',4,4'-benzophenone tetracarboxylic dianhydride in 50 mL of N,N-dimethylacetamide. React for 0.5 h under the protection of inert gas until completely dissolved, and then react at room temperature for 5 h to obtain a polyamic acid solution. Further purify it by recrystallization in methanol, filter, and then freeze-dry for 24 h to obtain polyamic acid powder.

[0034] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.02 part of glycidyl acrylate and 0.08 part of N-vinylcarbazole, and cool down to react at 2 °C for later use.

[0035] 3) Add 3 parts of cyclopentadienyliron dicarbonyl dimer and 0.04 part of hydrogen peroxide-benzoyl peroxide with a mass ratio of 3:7 to the mixture in step 2), and react at 2 °C for 3 h to obtain a mixed solution; 4) Add 0.1 - 0.15 parts of isoquinoline to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform at 200 °C to obtain a cation-π crosslinked polyimide conductive film.

[0036] Example 3 1) Ultrasonically disperse 6 parts of 4,4'-diaminodiphenylmethane and p-phenylenediamine with a mass ratio of 5:1 and 8 parts of 3,3',4,4'-benzophenone tetracarboxylic dianhydride in 50 mL of N,N-dimethylacetamide, react for 0.5 h under inert gas protection until completely dissolved, and react at room temperature for 5 h to obtain a polyamic acid solution. Recrystallize in methanol for further purification, filter, and freeze-dry for 24 h to obtain polyamic acid powder.

[0037] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.03 parts of aminoethylaminopropyltrimethoxysilane and 0.08 parts of 4-vinyl-1,3-dihydro-2H-indol-2-one, and cool down to 5 °C for standby reaction.

[0038] 3) Add 1 part of zinc tetraphenylporphyrin, 0.03 parts of potassium persulfate with a mass ratio of 6:1, and iron perchlorate to step 2), and react at 5 °C for 3 h to obtain a mixed solution; 4) Add 0.1 part of acetic anhydride to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform at 200 °C to obtain a cation-π crosslinked polyimide conductive film.

[0039] Example 4 1) Ultrasonically disperse 4 parts of 2-(4-aminophenyl)-1H-benzimidazol-2-amine and 4,4'-diaminodiphenylmethane with a mass ratio of 1:1 and 7 parts of 4,4'-oxydiphthalic anhydride in 50 mL of N,N-dimethylacetamide, react for 0.5 h under inert gas protection until completely dissolved, and react at room temperature for 5 h to obtain a polyamic acid solution. Recrystallize in methanol for further purification, filter, and freeze-dry for 24 h to obtain polyamic acid powder.

[0040] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.01 parts of aminopropyltrimethoxysilane, 0.08 parts of N-vinylcarbazole and 4-vinyl-1,3-dihydro-2H-indol-2-one with a mass ratio of 1:1, and cool down to 5 °C for standby reaction.

[0041] 3) Add 1 part of iron dinonylcarbonyl, 0.03 parts of iron perchlorate with a mass ratio of 1:4, and benzoyl peroxide to step 2), and react at 5 °C for 3 h to obtain a mixed solution; 4) Add 0.1 part of imidazole to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform it at 100 °C to obtain a cation-π crosslinked polyimide conductive film.

[0042] Example 5 1) Ultrasonically disperse 5 parts of 3,3'-dimethyl-4,4'-diaminodiphenyl ether and 2-(4-aminophenyl)-1H-benzimidazole-2-amine with a mass ratio of 2:3 and 7 parts of pyromellitic dianhydride in 50 mL of N,N-dimethylacetamide. React for 0.5 h under inert gas protection until completely dissolved, and then react at room temperature for 5 h to obtain a polyamic acid solution. Recrystallize it in methanol for further purification, filter it, and then freeze-dry it for 24 h to obtain polyamic acid powder.

[0043] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.02 part of aminoethylaminopropyltrimethoxysilane, 0.08 part of 3-vinyl aniline, and N-vinylcarbazole, and cool down to 0 °C for standby reaction.

[0044] 3) Add 1 part of lithium iron phosphate and 0.03 part of benzoyl peroxide to step 2), and react at 0 °C for 3 h to obtain a mixed solution; 4) Add 0.12 part of pyridine to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform it at 150 °C to obtain a cation-π crosslinked polyimide conductive film.

[0045] Example 6 1) Ultrasonically disperse 5 parts of 4,4'-diaminodiphenyl ether and 3,3'-dimethyl-4,4'-diaminodiphenyl ether with a mass ratio of 1:4 and 7 parts of pyromellitic dianhydride and 4,4'-oxybis(phthalic anhydride) with a mass ratio of 2:5 in 50 mL of N,N-dimethylacetamide. React for 0.5 h under inert gas protection until completely dissolved, and then react at room temperature for 5 h to obtain a polyamic acid solution. Recrystallize it in methanol for further purification, filter it, and then freeze-dry it for 24 h to obtain polyamic acid powder.

[0046] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.015 part of divinylbenzene, 0.1 part of 3-vinyl aniline and 4-vinyl-1,3-dihydro-2H-indol-2-one with a mass ratio of 1:3, and cool down to 2 °C for standby reaction.

[0047] 3) Add 2 parts of acetylferrocene and zinc tetraphenylporphyrin with a mass ratio of 3:4 and 0.05 part of iron perchlorate with a mass ratio of 4:5 to step 2), and react at 2 °C for 3 h to obtain a mixed solution; 4) Add 0.13 parts of triethylamine to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform it at 180 °C to obtain a cation-π crosslinked polyimide conductive film.

[0048] Example 7 1) Ultrasonically disperse 6 parts of 4,4'-diaminodiphenyl sulfone with a mass ratio of 3:5 and 4,4'-diaminodiphenyl sulfone and 6 parts of pyromellitic dianhydride with a mass ratio of 1:5 and 3,3',4,4'-biphenyltetracarboxylic dianhydride in 50 mL of N,N-dimethylacetamide, react for 0.5 h under inert gas protection until completely dissolved, and react at room temperature for 5 h to obtain a polyamic acid solution. Recrystallize it in methanol for further purification, filter it, and freeze-dry it for 24 h to obtain polyamic acid powder.

[0049] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.02 parts of glycidyl acrylate and 0.1 parts of 3-vinylaniline, N-vinylcarbazole, and 4-vinyl-1,3-dihydro-2H-indol-2-one with a mass ratio of 1:1:1, and cool down to react at 0 °C for standby.

[0050] 3) Add 3 parts of acetylferrocene, lithium iron phosphate with a mass ratio of 7:2 and 0.04 parts of potassium persulfate, benzoyl peroxide with a mass ratio of 3:1 to the solution in step 2), and react at 0 °C for 3 h to obtain a mixed solution; 4) Add 0.15 parts of pyridine to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform it at 130 °C to obtain a cation-π crosslinked polyimide conductive film.

[0051] Example 8 1) Ultrasonically disperse 6 parts of 2-(4-aminophenyl)-1H-benzimidazole-2-amine with a mass ratio of 1:6 and p-phenylenediamine and 8 parts of p-phenylenediamine in 50 mL of N,N-dimethylacetamide, react for 0.5 h under inert gas protection until completely dissolved, and react at room temperature for 5 h to obtain a polyamic acid solution. Recrystallize it in methanol for further purification, filter it, and freeze-dry it for 24 h to obtain polyamic acid powder.

[0052] 2) Dissolve the polyamic acid powder obtained in step 1) in 50 mL of N,N-dimethylacetamide. After complete dissolution, add 0.02 parts of divinylbenzene, aminoethylaminopropyltrimethoxysilane with a mass ratio of 5:2 and 0.12 parts of 3-vinylaniline, N-vinylcarbazole, and 4-vinyl-1,3-dihydro-2H-indol-2-one with a mass ratio of 1:2:3, and cool down to react at 3 °C for standby.

[0053] 3) In step 2), add 2 parts of acetylferrocene and cyclopentadienyldicarbonyliron dimer with a mass ratio of 3:7 and 0.06 parts of hydrogen peroxide and iron perchlorate with a mass ratio of 2:3, and react at 3 °C for 3 h to obtain a mixed solution; 4) Add 0.14 parts of pyridine to the mixed solution and react for 2 h. Then pour the solution into a mold and thermoform at 200 °C to obtain a cation-π crosslinked polyimide conductive film.

[0054] Comparative example: The difference from Example 8 is that no conductive polymer monomer is added in step 2).

[0055] The above 8 examples and comparative examples were respectively tested for tensile properties, electrical properties and ion spillage. The tensile strength can reach 1300 - 2500 MPa, with strong mechanical properties, and the thermal conductivity can reach 1.5 - 3.0 S·cm -1 , compared with the undoped one, its tensile strength and electrical properties are improved.

[0056] The test methods are as follows: 1) Tensile property test: According to GB / T1040.3—2006, the polyimide conductive film is made into a dumbbell shape, the sensor is 500 N, the tensile rate is 80 mm / min, the total length of the sample is 100 mm, the fixture spacing is 60 mm, and the gauge length is 25 m. 3 groups of samples are tested in parallel, and the results are averaged.

[0057] 2) Electrical property test: The conductivity of the polyimide conductive film is tested at 25 °C and calculated using the following formula: ; In the formula, D is the distance between the positive and negative electrodes of the polyimide conductive film, R is the resistance to be measured, and S is the electrode contact area 3) Ion spillage test: After the polyimide conductive film is treated in an acid-base buffer solution for 24 h respectively, the concentration of iron (III) is determined by aqua regia digestion method.

[0058] As Figures 1 - 3 shown, the polyimide conductive films of Examples 1 - 8 were tested for tensile strength, conductivity and ion leaching. The conductive polymer monomers added in Examples 1 - 3 are all monovalent, those in Examples 4 - 6 are all divalent, and Examples 7 and 8 are multi-component systems. Due to the larger delocalized π-bond range formed by the conductive polymer structure, as Figure 1 and Figure 2 shown, their tensile properties and electrical properties increase proportionally. It is confirmed that the introduction of conductive polymers has a dual effect on the mechanical and electrical properties of polyimide conductive films.

[0059] As Figure 3 shown, the polyimide conductive film was tested for ion leaching, and the leaching rates of the examples in Examples 1-8 were all within 10 -5 Hereinafter, it is sufficient to illustrate that the strategy of cation-π cross-linking ensures the stability of the material and further realizes the possibility of electron-ion conduction.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for preparing a cationic-π cross-linked polyimide conductive film, characterized in that: The following steps are involved: 1) preparing polyamic acid powder; 2) Dissolve 3-5 parts of polyamic acid powder in a solvent. After the polyamic acid powder is completely dissolved, add 0.01-0.03 parts of a modifier and 0.08-0.12 parts of a conductive polymer monomer, and react at 0-5°C to obtain an intermediate product. 3) adding 1-3 parts of transition metal organic complex and 0.03-0.06 parts of oxidant to the intermediate product, and after the reaction, adding 0.1-0.15 parts of dehydrating agent to the intermediate product for dehydration reaction to obtain a mixed solution; 4) The mixed solution is thermoformed at 100-200° C. to obtain a cationic-π cross-linked polyimide conductive film.

2. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 1, characterized in that: The preparation process of polyamic acid powder is as follows: Ultrasonic dispersion of 4-6 parts of diamine monomer and 5-8 parts of dianhydride monomer in N,N-dimethylacetamide, reacting under the protection of inert gas until completely dissolved, and obtaining a polyamic acid solution after reaction at room temperature; The polyamic acid solution was further purified by recrystallization in methanol, filtered and freeze-dried to obtain polyamic acid powder.

3. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 2, characterized in that: The dianhydride monomer is one or more of pyromellitic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride.

4. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 2, characterized in that: The diamine monomer is one or more of 4,4'-diaminodiphenyl ether, 2-(4-aminophenyl)-1H-benzimidazol-2-amine, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, p-phenylenediamine, and 2,2-bis(4-aminophenoxy)hexafluoropropane.

5. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 1, characterized in that: The modifier is divinylbenzene, glycidyl acrylate, aminoethylaminopropyltrimethoxysilane or aminopropyltrimethoxysilane.

6. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 1, characterized in that: The conductive polymer monomer is one or more of 3-vinylaniline, N-vinylcarbazole, and 4-vinyl-1,3-dihydro-2H-indol-2-one.

7. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 1, characterized in that: The transition metal organic complex is one or more of acetylferrocene, tetraphenylporphyrin zinc, cyclopentadienyldicarbonyl iron dimer, lithium iron phosphate, and dinonylcarbonyl iron.

8. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 1, characterized in that: The oxidant is one or more of hydrogen peroxide, potassium persulfate, ferric perchlorate and benzoyl peroxide.

9. The method for preparing a cationic-π cross-linked polyimide conductive film according to claim 1, characterized in that: The dehydrating agent is pyridine, isoquinoline, acetic anhydride, imidazole or triethylamine.

10. A cationic-π cross-linked polyimide conductive film prepared by the preparation method according to any one of claims 1 to 9, characterized in that: Its tensile strength reaches 1300-2500 MPa and its thermal conductivity reaches 1.5-3.0 S·cm -1 .

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